Influence of the dramatic fall of hormone replacement therapy (HRT) prescription on postmenopausal breast cancer incidence: The Austrian data

1529 Background: The Women's Health Initiative trial showed a significant increase in breast cancer risk among women using HRT. This publication led to a dramatic fall in HRT prescription worldwide. Several studies argued that the ensuing decline in breast cancer incidence among postmenopausal women was due to the reduced HRT prescriptions. We have investigated whether the strong decline in HRT prescription in Austrian women from 2002 onward was associated with a decrease in postmenopausal breast cancer incidence in Austria. Methods: Breast cancer incidence data were obtained from the National Austrian Cancer Registry. HRT prescription data were calculated using Pharmaceutical Benefits Scheme data. Hormone receptor expression data were taken from the pathology report of all patients with breast cancer, who were operated on at the Division of Special Gynecology, as well as the Department of Surgery, Medical University of Vienna (MUW), from 1998 to 2000, and 2005 to 2007, respectively. Chi-Square test was used to identify significant differences. Results: HRT prescription slightly increased from 1998 to 2000, but dramatically decreased by 70% after 2003, reaching a significantly lower level. When comparing breast cancer incidence data from 1999 and 2004, a nonsignificant trend toward a decreased incidence in 50- to 54-year-old women could be observed. Comparing predicted breast cancer incidence for 2004 with the actual incidence for 2004 in this group, a significant decrease could be demonstrated. Ten percent to 12% of all new breast cancers in Austria are treated at the MUW every year. Regarding histopathologic breast cancer parameters of patients treated at the MUW from 1998 to 2000 and 2005 to 2007, respectively, a nonsignificant decline of hormone receptor positive tumors in 50- to 54-year-old patients with breast cancer could be observed. Conclusions: The decline of HRT use in Austria is associated with a reduction in breast cancer incidence in postmenopausal women. Our data underline the association between HRT and breast cancer. No significant financial relationships to disclose.